But Renton police say that when they interviewed the man shortly after Chou disappeared on April 18, 2010, he had an alibi. He told police he had spent the night at a friend’s home and the friend backed him up.

Detectives now say Chou’s father was right.

The 22-year-old was arrested Wednesday in connection with Chou’s disappearance and presumed death. He is being held in King County Jail on $1 million bail and is expected to be charged by Monday, according to prosecutors.

The Seattle Times is not naming the suspect because he has not been charged.

According to a document of probable cause filed Thursday in King County Superior Court, the break in the case came last month when a former friend of the suspect went to police with information about Chou’s disappearance.

The friend told police he came forward because he believed the suspect had stolen from him and then denied it.

The friend told police that on the night Chou went missing the suspect had shown up at his house “covered in blood and had dirt up to his knees,” Renton police Detective Keith Hansen wrote in the probable-cause document.

According to police, the suspect and Chou used to date.

Hansen said that police then re-interviewed the suspect on Wednesday and he changed his story and told investigators that Chou was slain after “causing trouble in his life by threatening his new girlfriend,” according to probable-cause paperwork. The suspect took police to a vacant piece of land near the victim’s house where he claimed to have buried Chou, the document said.

On Thursday, police searched for Chou. Her remains have not yet been found.

According to charging documents, the suspect told police that another friend helped him bury Chou. That friend had provided the suspect with his alibi when he was interviewed by police shortly after Chou disappeared.

The friend changed his story when he was interviewed on Wednesday and led investigators to the same location where the body allegedly had been buried, the affidavit said. The suspect’s friend was arrested and released Wednesday. It’s unclear whether he will face charges.

Chou’s parents reported the Lindbergh High School senior missing on April 19, 2010, after she went for a walk around 7 p.m. the previous night and never came home, the affidavit said.

Chou’s father said he and his wife searched unsuccessfully for their daughter in Seattle, Oregon, Las Vegas and California.

They discovered they were part of a sad community of people, thousands strong, who know what it is like to have a loved one disappear, Chou’s father said.

On Thursday, Chou’s father said he had been prepared for the bad news that came from police this week.

“It’s not good news; we understand that,” he said. “But we learned a lot about missing-person cases and we had prepared ourselves for bad news. It is much better than going for 20 years without knowing anything.”